Two-stroke internal combustion engine



Dec. 13, 1938. w. HOWALD I TWO-STOKE INTERNAL COMBUSTION ENGINE FileJdOct. 29', 1936 s Shets-Sheet 1 Wernef' Hawaii 1! d3.

Dec. 13, 1938.

w. HOWALD I TWO-STOKE INTERNAL COMBUSTION ENGINE Fi led Oct. 29, 1936 5Sheets-Sheet 2 j Warn-e7 Howazcz J/L W W1 Dec. "13, 1938; w. HOWALD2,140,454

TWO-STOKE INTERNAL COMBUSTION ENGINE Fil'd'oot. 29, 1936 5 Sheets-Sheet3 r v Mw Werner HowcLZaZ 7 D6913, 1938. w. HOWALD 7 TWO-STOKE INTERNALCOMBUSTION ENGINE Fil edOot. 29, 1936 s Sheets-Sheet 4 he?" HawaiiTWO-STOKE INTERNAL COMBUSTION ENGINE w. HowALb 2,140,454

Patented Dec. 13, 1938 PATENT OFFICE TW STROKE INTERNAL COMBUSTIONENGINE Werner Howald, Zurich, Switzerland Application October 29, 1936,Serial 'No. 108,291 In Switzerland November 12, 1935 12 Claims.

' The invention relates to a two-stroke internal combustion enginewherein the sleeve valve car-- 7 ries out a movement parallel to itsaxis combined with an oscillating movement about its axis in such a waythat the absolute path of each point of the sleeve valve surfaceconstitutes a closed curve.

" The invention resides in the fact that the rotating movement of acrank shaft or of an eccentric is transmitted to the sleeve valve by aconnecting rod in such a manner that the component of the movementparallel to the axis of the cylinder of each part of the surface ofthesleeve valve circumscribing as above mentioned a closed curve, has ateach working stroke, during the time the piston has attained its highestvelocity, the same direction as the direction of movement of the pistonitself. Furthermore, the sleeve valve shows the greater accelerationduring the time that the sleeve valve controls the'working chamber thanduring the time that the Working chamber is completely closed and thecompression and combustion pressure attains its maximum value.

' Other objects will in part be obvious and in part be pointed outhereinafter. To the attainment of the aforesaid objects and ends, theinvention still further resides in the novel details of construction,combination and arrangement of parts, all of which will be first fullydescribed in the following detailed description, and then beparticularly pointed out in the appended claims, reference being had totheaccompanying drawings, in which:-

Fig. 1 is a diagrammatic vertical section of an engine embodying theinvention.

I Fig. 2 is a detail cross-section of the same on the line 22 .of Fig.1.

Figs. 3 and 4 show the path-time and control diagrams. v

vFig. 5 is a vertical'section of a portion of a radial cylinder engineembodying the invention; Fig. 6 is a detail section on the line 6-6 ofFig. 5. I

Fig. 7 is an enlarged detail section on the line 1-1 'of Fig. 5.

- Fig. 8 'is an enlarged elevation and part section of the lower portionof Fig. 5.

5 'The drawings show the cylinder l, sleeve valve '2 with driving pin2'; cylinder cover3, working piston 4, connecting rod 5, crank shaft 6,

f "two sleeve valve driving crank shafts I, eccentric l, crank pin 1',connecting rod 8, pivot-9,

eccentric sheave I 0, driving beam H-with slide guide II for theeccentric sheave, bearing l3, and gudgeon [4;

In the sleeve valve drive according to the invention shown in Figs. 1and 2 the driving shaft 1 rotates with the same speed as the crank shaft'6, and the horizontal component of the curve of movement C istransmitted from an eccentric l rotating in the same direction with thecrank pin 1" of the sleeve valve driving shafts l, and having no, oralmost no, angular displacement relatively to the crank pin 1, by meansof the eccentric sheave Ill to the slide guide ll of the driving. beam lI, while the vertical component is transmitted from the crank pin 1" bymeans of the connecting rod 8 to the pivot 9 mounted in the driving beamII, and partaking of the horizontal movement positively with this. Thispivot 9 therefore does not move along a vertical line but along a curvecorresponding with the curve of movement 0. This fact, as the pivot ,9moves in the same direction with the crank pin 1 but to a slight extentfrom the middle position, enables connecting rods 8 to be used of whichthe length is equal to the crank radius or still smaller, without theangular movement of the connecting rod 8 from the vertical becomingunallowably large.

In Fig. 1 (as shown at the right hand side) exhaust A is effected at theouter end of the working chamber, while the admission B of scavengingair and the admission B of the supercharging air or of the chargingmixture, takes place at the inner end of the working chamber.

The abscissa in Figs. 3 and 4 corresponds to one revolution of the crankshaft; the units are degrees or time units. For each position of thecrank shaft the corresponding position of the fixed control edges A0,and Au, of the outlet A, B0, and Bu, of the scavenging slots B, B's, andB'u, of the supe'rcharging slots B, of the moving control edges So, andSu, of the sleeve valve, and of the control edge' lo of the piston areshown. The arrows indicate the sense of rotation of the crank shaft, andthe corresponding movements of the piston and of the sleeve valve. Abovethe path-time diagram 4, are shown the corresponding velocity-timediagram and the accelerationtime diagram of the sleeve valve. The twolastmentioned diagrams show the points of highest velocity W, and of thehighest acceleration Po and Pu atthe higher and the lower dead point ofthe sleeve valve, and the two maxima of the acceleration P on each sideof the higher dead point. The phase difference between the movement ofthe piston and of the sleeve valve 'is marked a, and is equal to thedistance between the two horizontal tangents to the path-time diagramsof the piston and the sleeve valve respectively at the points of maximumamplitude. The phase difference does not impede so that the movement ofthe piston and of the sleeve valve has the same direction during thetime of maximum velocity of the piston at each stroke. As the Figs. 1, 3and 4 show, the sleeve valve controls the slots during the time of thehighest acceleration Pu, and the difference between the maximumacceleration of the two dead zones of the oscillating sleeve valve hasbeen made possible by making the ratio of crank radius to length of theconnecting rod as great as possibe. The two dead zones with differentmaximum accelerations Pu and P in the dead points, are separated fromeach other by the two zones of maximum velocity W; The above-mentionedratio can be :made equal to, smaller, or greater than 1, by imparting tothe beam II, besides its oscillating movement parallel to the cylinderaxis, also a movement at a right angle to the mentioned axis. This isthe reason for the movements shown in Figs. 1 and 4 which areparticularly favorable for controlling.

The diagram according to Fig. i dilfers from the diagram 3, only in thatthe section b representing the scavenging time, is made smaller in orderto increase b representing the scavenging time cross section.

The ordinates of the vertically shaded areas a, b and b, show the courseof the internal slot heights which multiplied by the corresponding slotwidths, give the cross-sectional areas of the exhaust A into theatmosphere or into an exhaust turbine, preferably a free exhaustturbine, of the inlet B for the scavenging air, and of the inlet B forthe supercharging air or charging mixture. By reversing the direction ofrotation of the crank shaft and of the sleeve valve driving shaft, or,what amounts to the same thing, by turning the sleeve valve drivingshaft relatively to the crank shaft corresponding to an equal or almostequally large lag, the exhaust A instead of being effected unseparatedat the outer, end of the working chamber, may be effected at the innerend of the working chamber separately into exhaust A to the pre-exhaustturbine, and exhaust A into the atmosphere or into the exhaust of thepreexhaust turbine or into the subsequent exhaust and scavenging gasturbine, while the inlet B of the scavenging air and the inlet B of thesupercharging air or of the supercharging mixture, instead of beingeffected separately at the inner end of the Working chamber is effectedunseparately at the outer end of the working chamber through the inlet Bas indicated at the left-hand side of Fig. 1.

In order to avoid the necessity of providing two separate sleeve valvedriving shafts I for each sleeve valve, the arrangement of the drivingshafts I is such that two driving beams I I are coupled to one drivingshaft! (Figs. 5-8), in such a manner that for one driving beam I I thehorizontal component of the movement curve is produced by means of theeccentric 1', and the eccentric sheave I0 and the vertical component bymeans of the crank pin I and the connecting rod 9, while for the otherdriving beam II only the vertical component is produced by means of thesecond crank gear, this movement being necessary for the parallelguiding of the driving beam I I. By the arrangement of the sleeve valvedriving shafts in the corners of the crankcasing, the bores for thereception of the bearing bushes no longer lie directly in the line ofpower transmission from the working cylinder to the working crank shaftbearing, which is of considerable importance for the durability of thehighly stressed crank casing. The length of the connecting rods of thedrive of the vertical reciprocating movement of the sleeve valve is soshort that conencting rods can no longer be used, but the diameter ofthe running surface of the pivot 9 (Figs. 1, 2), must be made so largethat the crank pin comes to lie within the running surface of the pivot9, the connecting rod thus becoming a round disc, or the running trackis divided into two running track sectors, symmetrical to the connectingline between the centers of the crank pin and the pivot center, one ofthe sectors 9', that surrounding the crank pin, of the same radius asthe connecting disc, the other 9" of smaller radius.

As the running surfaces 9 and 9" of the connecting discs 8, and also thecorresponding running surfaces of the driving beams II about the center9 are constructed spherically, a uniform supporting of the runningsurfaces both between the connecting discs 8 and the driving beams II isalways obtained, and the connecting discs 8 and the crank pins of thesleeve valve driving shaft I as the connecting discs 8 adjust themselvesautomatically, in the case of inaccuracies or slight deformations of thecrank pin in consequence of the spherical running tracks 9' and 9". Asthe running track of the slide guide II, as also that corresponding withthe eccentric sheave in, are constructed cylindrically in a plane atright angles to the plane of movement formly over the entire width; inaddition, the

driving beam is prevented from turning about the center 9 of thespherical running surfaces 9 and Q". The transmission of the movementfrom the driving beam II to the pivot 2' of the sleeve valve 2, isefiected through the bearing I3 which is secured to the driving beam I lby means of two set screws, and is centered by cylindrical centeringfrom the center of the gudgeon I4, and by the gudgeon I4 is mountedspherically in the bearing casing I3. In spite of the offsetting of thedriving beam II, no tilting moments act on this, as the centers of thetwo connecting discs 8 and of the gudgeon I4, are located in one planeand the vertical forces are balanced. The torque, resulting from thenormal pressure of the connecting disc 8 and the distance I and I of thecentral planes of the connecting discs 8 and of the eccentric I, istaken up by the spherical'running surfacesbetween the driving beam IIand the connecting discs 8,'and transmitted to-the connecting discs 8,which in turn are prevented from axial movement by the disc, I5and thescrew l6. q 1

From the foregoing description, taken in connection with theaccompanying drawings, it is thought that the construction, operationand advantages of the invention will be clear to those skilled in theart.

I claim:

1. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve cludes two additional crank shafts locatedin a valve, a piston, a crank shaft and a connecting rod between saidcrank shaft and said piston;

means to operate said valve, which means includes two additional crankshafts, a driving beam, a driving pivot connecting said beam to saidvalve, connecting rods connecting said beam to the cranks of saidadditional crank shafts for raising and lowering said beam, and othermeans connecting one of said cranks with said beam for moving said beamlaterally while it is being raised and lowered.

3. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve raising and lowering said beam, and othermeans connecting one of said cranks with said beam for moving said beamlaterally while it is being raised and lowered, said cranks andlast-named connecting rods and said other means being so positioned andproportioned that on a, path-time control diagram of the engine the zoneof movement of the valve during the control of the perative area showsgreater acceleration than during that period during which the pressuresof compression and combustion attain their maxi- 'mum values incompletely closed operative spaces.

4. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft, and aconnecting ma between said crank shaft and said piston;

means'to operate said valve, which meansincludes two additional crankmechanisms, a driving beam, a driving pivot connecting said beam '.withsaid valve,said additional crank mechanisms including meanscooperatively connected to said driving beam by virtue of which thecomponent of movement of said driving beam at right angles to the axisof the valve is effected by one of said additional crank mechanisms andthe component of movement parallel to the axis of said valve is effectedby the other additional crank mechanism, one of said additional crank'mechanisms also including means by virtue of which the movement of thevalve during the control of the operative area accelerates more.gr'eatly than during that period at which the pressures ofcompression-and combustion attain their maximum values.

5, In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston;

means to operate said valve, which means includestwo additional crankshafts located in a plane substantially normal to the axis of thepiston, a driving beam, connecting rods connecting the cranks of saidtwo additional crank shafts to said beam, said beam lying approximatelyparallel to said plane, and a driving pivot connecting said beam to saidsleeve valve, a slotted guide carried by said beam and an eccentricsheave movable in said guide, and an eccentric on one of said twoadditional crank shafts and carrying said eccentric sheave, saideccentric guide and said eccentric sheave having concave and convexabutting faces respectively.

6. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston; means tooperate said valve, which means includes two additional crank shaftslocated in a plane substantially normal to the axis of the piston, adriving beam, connecting rods connecting the cranks of said twoadditional crank shafts to said beam, said beam lying approximatelyparallel to said plane, a driving pivot connecting said beam to saidsleeve valve, a slotted guide carried by said beam and an eccentricsheave movable in said guide, an eccentric on one of said two additionalcrank shafts and carrying said eccentric sheave, and means to confinesaid beam to movement in one plane.

7. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston, means tooperate said valve in such a manner that the sleeve valve moves parallelto its axis and around its axis, the operating means including twoeccentric rotating pins, one of said pins having a larger eccentricitythan the other one, a driving beam, a driving pivot connecting said beamto said valve, a connecting rod connecting said beam to the rotating pinwith the larger eccentricity and producing substantially the movement ofthe sleeve valve parallel to its axis.

8. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston, means tooperate said valve in such a manner that the sleeve valve moves parallelto its axis and around its axis, the operating means including twoeccentric rotating pins, one of said pins having a larger eccentricitythan the other one, a driving beam, a driving pivot connecting said beamto said valve, a connecting rod connecting said beam to the rotating pinwith the larger eccentricity and producing substantially the movement ofthe sleeve valve parallel to its axis, the driving pin with the smallereccentricity being connected to the beam and producing substantially themovement of the sleeve valve around its axis.

9. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston, means tooperate said valve in such a way that the sleeve valve moves parallel toits axis and around its axis, the operating means including twoeccentric rotating pins, one of said pins having a larger eccentricitythan the other one, a driving beam, a driving pivot connecting said beamto said valve, a connecting rod connecting said beam to the rotating pinwith the larger 7 eccentricity and producing substantially the movementof the sleeve valve parallel to its axis, the driving pin with the,smaller eccentricity being connected to the beam by a slide running onthis pin and in a track of the beam and producing substantially themovement of the sleeve valve around its axis.

10. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston, means tooperate said valve in such a way that the sleeve valve moves parallel toits axis and around its axis, the operating means including twoeccentric rotating pins, one of said pins having a larger eccentricitythan the'other one, a driving beam, a driving pivot connecting said beamto said valve, a connecting rod connecting said beam to the rotating pinwith the larger eccentricity and producing substantially the movement ofthe sleeve valve parallel to its axis, the driving pin with the smallereccentricity being connected to the beam by a slide running on this pinand in a track of the beam and producing substantially the movement ofthe sleeve valve around its axis, the connecting rod having a sphericalrunning surface in the beam, and the slide having a cylindrical runningtrack in the beam.

11. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston, means tooperate said valve in such a Way that the sleeve valve moves parallel toits axis and around its axis, the operating means including twoeccentric rotating pins one of these pins having a larger eccentricitythan the other one, a driving beam, a driving pivot connecting said beamto said valve, a connecting rod connecting said beam to the rotating pinwith the larger eccentricity and producing substantially the movement ofthe sleeve valve parallel to its axis, the two driving pins beingarranged side: by side on the same driving shaft.

12. In a sleeve valve two-stroke internal combustion engine whichincludes a cylinder, a sleeve valve, a piston, a crank shaft and aconnecting rod between said crank shaft and said piston, means tooperate said valve in such a Way that the sleeve valve moves parallel toits axis and around its axis, the operating means including twoeccentric rotating pins one of these pins having a larger eccentricitythan the other one, a driving beam, a driving pivot connecting said beamto said valve, a connecting rod connecting said beam to the rotating pinwith the larger eccentricity and producing substantially the: movementof the sleeve valve parallel to its axis, the effective length of theconnecting rod being about as large as the eccentricity of the drivingpin.

WERNER HOWALD.

